Refrigerating apparatus and method



March 14, 1939. L. A. PHILIPP. 2,150,599

REFRIGERATING APPARATUS AND METHOD Filed Nov. 25, .1952 2 Sheds- Sheet 1 14: a: W i 4: 87

a2 F a? WHILE:-

J7 INVENTOR.

Lnwqsua' A. PIIILIPP ATTORNEY.

March 14, 1939. L. A. PHILIPP flllllllllll 2 Sheets-Sheet 2 REFRIGERATING APPARATUS AND METHOD Filed Nov.-23, 1932 I lillllltli!!!Illltlllllllldlllliillllritlll Patented Mar. 14, 1933 PATENT OFFICE,

BEFBIGERATING APPARATUS AND'METHOD Lawrence A. Philim), Detroit, Mich" assignor, by

mesne assignments, to Nash-Keivinator Corporation, Detroit, Mich., a corporation of Maryland Application November 23, 1932, Serial No. 644,061

7 Claims.

This invention relates to refrigerating apparatus, and more particularly to multiple temperature refrigerating apparatus.

One of the objects of my invention is to provide an improved multiple temperature refrigerating system wherein different temperatures are maintained in different evaporators, by controlling the heat transfer characteristics of some or all of the refrigerant evaporators.

Another object of my invention is to operate the aforesaid system with substantially equal pressures in the different evaporators and to maintain a temperature differential between the evaporators by retarding the flow of refrigerant through some of said evaporators. 7

Another object of my invention is to arrange for maintaining different temperatures in a refrigerating system by selectively controlling the heat transfer characteristics of one or all of the refrigerant evaporators in said system.

Another object of my invention is to provide an improved method for maintaining a temperature differential between a number of the diiferent refrigerant evaporators of the refrigerating system.

Another object of my invention is to provide a refrigerating system of the type in which liquid and gaseous refrigerants are circulated through the different evaporatofs" at substantially equal pressures, and to arrange for retarding to a predetermined amount the flow of refrigerant through some of said evaporators to vary the heat transfer characteristics of some of said evaporators to thereby maintain a predetermined temperature differential between the said evaporators.

Another object is to arrange for injected expanded refrigerant from a common source into each of the aforesaid evaporators to insure substantially uniform temperatures throughout the various parts of each evaporator without affecting the temperature differential between the various evaporators.

Another object of my invention is to provide an improved refrigerating system in which a temperature differential. is maintained between. a number of refrigerant evaporators by the use of primary and secondary refrigerants and a simplifled system of controls therefor.

Further objects and advantages of the present invention will be apparent. from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a view shown partly diagrammatically and partly in cross section of a refrigerating v apparatus embodying features of my invention;

Fig. 2 is a view taken along the line 2-2 of Fig. 1;

Fig. 3 is a view taken along the line 3-3 of Fig. 1; I

Fig. 4 is an enlarged fragmentary view shown in cross section of a valve mechanism used for controlling the flow of refrigerant in the apparatus shown in Fig. 1;

Fig. 5 is a view in cross section of a modified. form of refrigerating apparatus embodying features of my invention;

Fig. 6 is a view taken along the line 6-6 of Fig. 5; and

Fig. 7 is a diagrammatic representation of a modified form of refrigerating apparatus embodying features of my invention.

Mechanical refrigerating systems wherein different temperatures arev maintained generally comprise an intermittently operatedrefrigerant condensing unit and a number ofdifferent refrigerant evaporators .operatively associated with the condensing unit, the number of refrigerant evaporators depending upon the number of compartments to be .refrigerated. Systems of this type require the provision of some means for maintaining difierent temperatures in the different evaporators.

The systems heretofore .used customarily included pressure reducing valves at the inlet of eachevaporator and pressure responsive valves at the outlet of some or all-of the evaporators. The pressure responsive valves prevented the.

withdrawal of refrigerant vapor and heat from the different evaporators until predetermined pressures existed therein. By this arrangement" Another type of system in which different tem- V peratures can be maintained is the so-called slopover system,"which includes-a number of different evaporators placed. at different heights so that refrigerant in excess of a certain amount flows into an evaporator located on a lower level. Toobtain different pressures in different evaporators in systems of this type, it has been proposed to throttle the vapor lines of some of. the evaporators to maintain different pressures, and consequently, different temperatures in the diflerent evaporators. Systems of this type are unsuitable for installation in ice cream cabinets wherein it is very desirable to have the various evaporators positioned on the same horizontal plane. Furthermore, there is lacking the selectivity of temperatures in the different evaporators. it being necessary in such systems to maintain a lower temperature in the uppermost evaporator, for the reason that higher-pressures in the evaporators located at lower levels prevents the flow of liquid refrigerant from the uppermost evaporator to said other evaporators.

In accordance with my invention, I arrange a plurality of refrigerant evaporators in open communication with each other, and I also. arrange to retard the flow of refrigerant through some of said evaporators by restricting the outlet of some of said evaporators to thus decrease the circulation of refrigerant through some of said evaporators to thereby vary the heat transfer characteristics of the different evaporators. By this arrangement, I maintain a predetermined temperature diiferential between some or all of the different evaporators without the use of pressure reducing valves for each evaporator and without the use of pressure responsive valves.

Referring now to the drawings for a detailed description of the invention, the numeral 20 desi nates, in general, a cabinet of the type suitable for storing ice creams, frozen packaged goods, and the like, to be kept at low temperatures. The cabinet is constructed of insulated walls 24 which cooperate to form a compartment 26. Within the compartment is disposed a refrigerant low side 28 of a refrigerating system. A refrigerant high sidevor condensing element 30 of the system is operatively associated with the low side.

The refrigerant low side comprises, in general, a header 34 adapted to contain a quantity of liquid refrigerant. The header is preferably of tubular formation and is provided on one end thereof with a valve plate 36 clamped between a cover plate 38and an end ring 39, which is preferably welded to the tubular wall of the header. Depending from the lowermost portion of the header is a stand pipe or refrigerant accumulator 4|; which is in open communication with the interior of the header. Refrigerant expansion coils, evaporatorsor conduits 43, 44 and 45, are 'connected to one end thereof with the lower end of the accumulator by means of a refrigerant sup-.

' ply conduit 50 which is in open communication with each of the expansion coils 43, 44 and 45 and with the interior of the refrigerant accumulator. Each of the refrigerant evaporators 43, 44 and 45 is connected on their upper ends to the header above the level of liquid refrigerant thereinby means of vapor conduit 52 and extension conduits 54, 55 and 56, of the expansion coils 43, 44 and 45, respectively. Suitable float valve mechanism is provided within the header for the purpose of maintaining a. substantially constant level of liquid refrigerant therein. The float, valve mechanism includes a float 60 and a valve 62 which cooperate with valve seat 63 to control the passage of liquid refrigerant from the high pressure side of the condensing element to the low pressure side or expansion conduits. The header" 34 and accumulator 4| are supported by an enclosure 65, which is. constructed preferably of thin I sheet metal.

around and in good thermal contact with tanks or sleeve members 61, 68 and 69, respectively. The tanks or sleeve members are arranged to accommodateone or more open top food containers 12. The cabinet is provided with removable covers or lids 13 for ready access to the containers.

The refrigerant condensing element 30 comprises, in general, a compressor 15, condenser 11, motor 18 for operating the compressor, and a liquid refrigerant receiver 80. The compressor withdraws gaseous refrigerant from the cooling or evaporating elements through a vapor conduit 82, compresses the gaseous refrigerant and delivers it to the condenser wherein it is liquefied and from which it is delivered to the liquid refrigerant receiver. Liquid refrigerant' is delivered to the various evaporators through a supply conduit 84. An automatic switch is provided for controlling the operation of the motor in response to changes in pressure in the vapor conduit in the well known manner.

Suitable connections 81 and 88 are provided in the cover plate to which the conduits 82 and 84 are connected, respectively. Liquid refrigerant passes from the supply conduit 84 to the connection 88 and when the float valve is opened the liquid refrigerant passes through the oriflced valve seat 63 into passage 90 which communicates with a conduit 32. Liquid refrigerant passes through the conduit 92 whence it is injected into the inlet end of the supply conduit 50 by mans of an injector or nozzle 35 in a manner about to be described.

During periods when the float valve is open, liquid refrigerant passes through condluit 91 and injector 95 into conduit 50. Since the accumulator 4| is in open communication with the header 34 and the conduit 50 is in open communication with the accumulator, the level of liquid refrigerant within the expansion conduits 43, 44 and 45 will normally be the same as in the header 34. When refrigerant is being injected into the supply conduit 50, a portion thereof will flow through the outlets or upper, ends of the expansion conduits 43, 44 and 45 and into the header 34 until the float rises sufficiently to close the float valve 62.

From the foregoing, it will be apparent that the large volume of liquid refrigerant in the header and accumulator will cause evaporated refrigerant in the expansion conduit to pass through the outlet ends of the expansion conduits and into the gas space in the header due to the resistance offered by said large body of liquid. Under some circumstances, it has been found that the evaporation of refrigerant has been so great in the expansion conduits as to pick up liquid refregerant and deliver it to the header, whence it descends into the accumulator to be re-circulated.

In order to, promote and to initiate the ebullition and to promote the circulation of liquid refrigerant through the expansion conduits, the injector has been provided. This prevents the superheating of liquid refrigerant in the expansion conduits and tends to maintain uniformtemperatures throughout the various parts of each of the expansion conduits or evaporators. The injector is formed by restricting the outlet end 98 of the conduit 92. 98 is disposed part way into a fitting l 00 to which The restricted end the supply conduit 50 is connected. A recessed per part is secured to the accumulator, preferably by welding. The injector is adapted to inject supply conduit 50 where the pressure is low.

Consequently, the injector provides a means of positively circulating liquid refrigerant in the various refrigerant evaporators. It will also be noted that the gaseous part of injected refrigerant immediately initiates the ebullition of refrigerapt in the expansion conduits uponits admission thereto- Also, the gaseous part of the injected refrigerant, in addition to starting the ebullition in the expansion conduits, promotes ebullition throughout its passage therethrough.

By positively circulating, initiating and promoting ebullition andv the circulation of refrigerant, both liquidand gaseous, in the refrigerant evaporators, the oil pumped thereinto by the compressor is readily returned to the compressor through the vapor conduit 82 by reason of .its entrainement with the evaporated refrigerant.

In maintaining ice creams in a frozen condition, the user of the apparatus is frequently called upon to maintain different ice creams at different temperatures, such,- for example, as bulk ice cream, small package ice cream and brick ice creams. Under these conditions, it has been found desirable'andeconomical to operate the different expansion coils of the refrigerant low side at different temperatures suitable for refrigerating the different types of food articles.

In accordance with my invention, I provide for maintaining each of the evaporators either at the same temperature or for selectively varying the temperatures of each or all of said evaporators, depending upon the type of food articles to be stored. This is accomplished by merely providing manually operable valves III) and H2 which are disposed in the extension conduits '55 and 54. of the refrigerant evaporators 44 and 43. The valves are'for controlling the amount of refrigerant which is circulated through the evaporators 43 and 44. Preferably, these valves are of the well known packless type. The valves III) and H2 are arranged so that the flow of refrigerant through expansion conduits 44 and 43'may be retarded to a predetermined amount or may entirely shut olf. When the flow of refrigerant is-entirely stopped through one of said conduits no refrigeration Willtake place in the respective expansionconduit. When the valve is operated to retard the flow of refrigerant through one of said/evaporators, the refrigerating effect of unrestricted outlet passage. .These valves are not said'evaporator will be reduced and will be less' than the evaporator which is provided with an of the pressure responsive type but are of the type which positively shut off the flow of refrigerant through an expansion coil or'permit a predetermined amountto flow through said coil without variation, except when manually ad- 'justed.

decrease the amount of liquid refrigerantas well as the amount of gaseous refrigerant which is being circulated through an evaporator. By slowing up the circulation of refrigerant through one of said evaporators and keeping the liquid level down, the rate of heat transfer has been lessened, which effects'the heat transfer characteristics of the'respective evaporator to thus maintain a higher temperature in said evaporator than in other evaporators in which the flow of refrigerant is unrestricted. It will also be noted that the refrigerant supply conduit is in open communication with the inlet ends of each of the refrigerant expansion coils, and for this reason the pressures in the various expansion coils will be substantially equal. Furthermore, it will be noted that the temperatures of the various evaporators may be selectively controlled by simply manipulating valves IIO and/or 2-. j

During the on-phase of the refrigerming cycle, the condensing element withdraws evaporated refrigerant from the gaseous refrigerant space in the header '34 and from the refrigerant expansion conduits 43, 44 and 45. During this time it has been found that there is a slight pressure difference equal to only a few inches of liquid refrigerant pressure on opposite sides of the valves H and H2 in conduits 55 and 54 when sure difference causes a slight amount of liquid refrigerantin theexpansion conduits 43 and 44 to be forced into the supply conduit 50 to other expansion conduits or into the refrigerant accumulator. During the off-phase of the refrigerating cycle. and when thevalves are but partly closed, it has been found, however, that the pressures on opposite-sides of the valves are substantially, if not entirely, equal. Under these circumstances, the amount of liquid refrigerant in each of the expansion conduits is equal.

In order to arrange for the ready access of the valves III) and H2, I have provided an opening I20 in the top wall of the cabinet, which is closed by removable cover or lid I22. This places the system in readiness for the selective control of temperatures in the different refrigerant evaporators.

In refrigerating systems of the type herein described wherein diiferent temperatures are maintained in the different evaporators, it has been found desirable to provide means for preventing the transfer of heat from an evaporator maintained at a higher temperature to an evaporator operating at a lower temperature. For this purpose, I provide insulating material I25 between and I52,'respectively. \Liquid refrigerant is supplied to and the gaseous refrigerant is withdrawn from the primary evaporator I45 in. a like manner as refrigerant is supplied to and withdrawn from evaporator 45, shown in Fig. 1, which is, briefly, through a supply. conduit I55 from the .the valves are partly closed. This slight presrefrigerant accumulator and from the injector (not shown), and the gaseousmefrigerant is withdrawn into. the refrigerant header through a vapor conduit I51. The primary system, in addition to the evaporator I45, supply conduit I55, vapor conduit I51, header and accumulator, also includes a cooling plate I60. The inlet of the plate I60 is connected to the supply conduit I55 by means of a conduit I62, and the outlet of the plate I50.1s connected to the vapor conduit I51 by conduit I64. The condensing element 7 30, shown in Fig. 1, may be used as part of th primary system. 7 r

Suitably secured to opposite sides of plate I60 are metal members I10 and I12 to provide chambers I14 and I15 for condensing evaporated refrigerant in the secondary systems. The secondary evaporator I48 is connected to chamber I14 b'ya liquid inlet conduit I16 and an outlet conduit I18. Secondary refrigerant evaporator I41 is connected to chamber I15 by a liquid inlet conduit I80 and a refrigerant return conduit I82. During operation of the apparatus, liquid refrigerant is evaporated in the evaporators I41 and I48 whencethe evaporator refrigerant passes through conduits I82 and I18 to chambers I15 duits I80 and I15.

and I14, respectively, to be condensed. The condensed refrigerant is recirculated through con- In order to control the temperatures in the secondary systems, I provide valves I85 and I86 which are disposed in conduits I18 and I82, re-' spectively. These valves are preferably of the well known packless type like previously described and are employed to retard the flow of refrigerant through the secondary refrigerant evaporators to vary the heat transfer characteristics with respect to the primary evaporator and liquid refrigerant supply conduit I94 is connected to each evaporator and in open communication therewith. At the outlet ends of the evaporators I and I9I are disposed valves I96 and I91, respectively. These valves are of the type which may be manually set to retard the flow of refrigerant through the evaporators I90 and I 9I in varying amounts. To the valves I98 and I91 are connected thermostatic bulbs 200 and 20I,

respectively. These bulbs are filled with expansible fluids and are arranged to be responsive to changes in temperatures of the'evaporators I90 and I9I for varying automatically the amount of restriction offered by the valves I96 and I91. This arrangement may be advantageously used in the event insulating material is not used between the diflerent evaporators to compensate for the transfer of heat from one evaporator to another when one is operated at a higher temperature than the other. However,the thermostatic bulbs are not provided for intermittently opening and closing the outlet passages of the evaporators but are merely for the purpose of cooperating for heat transfer to maintain substantially constant temperatures in each evaporator. frigerant header, injector. accumulator and con- This system may be connected to a redensing element, the same as shown in Fig. 1. However, the operation of the motor-compressor unit of such condensing element may be convtrolledby means of a thermostatic bulb I30 which is responsive to changes in temperatures of evaporator I92 and which may be connected to the M automatic switch 85.

;Although only a preferred form of the invention has been illustrated, and that form de- 'be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What I claim as my invention is:

l. The method of refrigeration which consists in maintaining a temperature differential between a number of different refrigerant evaporators by maintaining therein substantially equal levels of liquid refrigerant during the nfl-phase only of the refrigerating cycle and maintaining substantially different levels of liquid refrigerant in the diiferent evaporators only during the onphase of the refrigerating cycle.

2. Refrigerating apparatus comprising, in combination, a number of different refrigerant evaporators, a conduit inopen communication with said evaporators, means'for injecting expanded refrigerant into said conduit means for controlling the flow of refrigerant through said evaporators and an outlet chamber in open communication with each evaporator whereby injected refrigerant or liquid refrigerant entrained with evaporated refrigerant is free to pass continuously through each evaporator at all times.

3. Refrigerating apparatus comprising, in combination, a cabinet, a plurality 6f open top sleeves disposed in said cabinet, a number of different refrigerant expansion conduits, one being wrapped around each of said sleeves, a liquid refrigerant feed line common to each of said evaporators and inopen communication therewith, outlet conduits for said evaporators and in open communidifferential between the different zones.

5. Refrigerating apparatus of the type wherein multiple temperatures are maintained, including a plurality of refrigerant evaporators, one of said evaporators having an outlet restricted to the flow of refrigerant therethrough, means connecting the inlet of the evaporators in open communication' with the outlet of the evaporators whereby refrigerant is free to pass at all'times through said means and evaporators, said restricted portion maintaining the temperature of oneof said evaporators above another evaporator of the apparatus, and means for injecting refrigerant into said apparatus. T

6. A refrigerating system comprising a plurality of refrigerant evaporators interconnected in such-a mannerthat refrigerant is free to pass continuously therethrough, means for injecting refrigerant into said evaporators, and means for restricting the passage of refrigerant through one ous refrigerant from said evaporators, and means controliingthe withdrawal of gaseous refrigerant from one of said evaporator-s for maintaining said one evaporator at a predetermined temperature higher than that of the others of said evaporators. 5

LAWRENCE A. PHILIPP. 

